Detect Skipping Extruder?
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Is it possible to detect when Extruder is skipping? similar to how you can do sensorless homing using just the stepper
if skipping can be detected can an error pop up when it happens?
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You could/can with a filament monitor.
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@Adamfilip yes, you can set stall detection, assuming you have a board that supports it (most do)
https://docs.duet3d.com/en/User_manual/Reference/Gcodes#m915-configure-motor-stall-detection -
@jay_s_uk Can you set it to run a macro?
Rn Action to take on detecting a stall from any of these drivers: 0 = no action (default), 1 = just log it, 2 = pause print, 3 = pause print, execute /sys/rehome.g, and resume print. See notes for RRF v3.4
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@Adamfilip you have given me an idea ... if the stall detection of the extruder was on the fist layer , could you auto baby step the nozzle away from the bed ?
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@moth4017 interesting idea to compensate for being too close on layer 1
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@Adamfilip yes
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@Adamfilip yes. You can set it via macro or the console
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@Adamfilip be aware that stall detection may not work well at typical extruder speeds, see this:
YMMV and you do need to tune it in.
From 3.4 your detected stalls will be handled by the event system:
In RRF v3.4 and later there is no longer a distinction between R2 and R3; both cause an event to be created when the driver stalls. To handle the event, RRF calls driver-stall.g passing the stalled local driver number in param.D and the CAN address of the board concerned in param.B. File rehome.g is no longer used. If file driver-stall.g is not found then the print is paused without running pause.g and the error is reported.
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@Adamfilip a caveat is that if the extruder is driven by a TMC2209 then the driver would have to be in stealthChop mode for stall detection to work, and using stealthChop on extruder motors is almost certainly a bad idea. It might be OK using TMC2660 or TMC2160/5160 drivers, although stall detection is easier at reduced current.
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I started thinking of how stall detection works, and I was wondering if it's possible to monitor the extruder stepper voltage. It seems to me that if you have a filament run out, the voltage would suddenly drop significantly as the motor force would drop. On the other end of the spectrum, a filament snag would cause the motor voltage to spike before the extruder started to grind, leading to a reduction in motor torque as the filament disappeared from under the drive gear. So, is it possible to monitor the extruder stepper voltage, and have an acceptable range? Any voltage outside of that range would trigger a problem.
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@RandyL00123 I'm not sure there is a way to monitor that in duet/DWC ,
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